The meaning of liberal

Courtesy of Voteview, I'm looking at the ratings of the first US Senate elected in the 20th century (57th Congress) and, in particular, the record of the most liberal senator, one Anselm McClaurin (D-MS), whose 1st coordinate is -0.768 [1].

But what does the score mean [2]? Or rather, what does being liberal in 1901 (or, the limiting case, 1789) mean?

There is, of course, a great deal of business transacted in the Senate otherwise than through roll call votes, almost none of it accessible online, so far as I'm aware [3]. But, since the model works on roll calls only, that impediment is rather lessened [4].

The ideological content of most of the 57th Congress roll calls is not readily analysed along a liberal-conservative axis, as those terms are understood today.

High frequency topics are the Panama Canal, the post-invasion disposition of the Philippines, the legal regime for the carriage of overseas mails, Chinese immigration and the building of Union Station in Washington.

For instance, on February 24 1902, McLaurin voted against (RC 26) passage of the Philippines relief bill (HR 5833) - a perfect party-line vote. He had previously supported an amendment (RC 19) to required two witnesses in treason trials, and opposed (RC 21) another reducing the tariff on US imports from the Philippines from 75% to 50%. (Love those free-trade Yanks, boy...)

Where's the ideology? On the tariff issue, for instance. Classically, Southern Democrats, representing mainly primary producers, favoured low tariffs: growers of cotton and tobacco needed no protection themselves against imports, but suffered from the high tariffs imposed on imports of the manufactures they needed to buy.

By 1901, there was something of a textile industry in the South in need of protection against imports of piece-goods. But I doubt whether the Philippines were much of a threat at the time in this market!

The DW-NOMINATE 1st coordinate scores for the seven Dems show most at the low - liberal - end of the range (Gibson is 29th most liberal of 32 Dem senators). But other liberals from the same sections voted against the tariff amendment (as evident from this list of the top ten Dem liberals):

An useful paper is Poole and Rosenthal's D-NOMINATE After 10 Years, which briefly explains the math behind the system - calculus alert! - and has useful charts. And the rather less mathier paper NOMINATE: A Short Intellectual History outlines the genesis of the system. There are others from Poole here.

Though I shouldn't be surprised to learn that Lexis supplies it, for a price.

Though the information on votes available via Voteview is brief, and does not allow for subtlety.

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Use of liberal to mean having a low DW NOMINATE score is a question-begging approximation - but useful, as meaning something (albeit misleading) rather than nothing.

And there is something with negative numbers that screws with the brain: a guy batting -1.000 is liberal in the highest degree, but, numerically, his score is the lowest.